Direct-current generator



b W'.v Hc T HQLEN ETAL 2,418,471

DIRECT CURRENT GENERATOR Filed July 12, 1944 2 sheetsheet 2 5a FIG. 6. 9

e 52 is WH I HOLDEN f Wmqg f5 R MORTO/v ATTORNE V Patented Apr. 8, 1947 I Willie-m H. T. Holden, Woodside, and Edmund R,

Morton, Brooklyn, N. Y., assignors to Bell Telephone Laboratories, Incorporated, New York,

N. Y., a corporation of New York Application July 12,

10 Claims.

This invention relates to a direct current genf.

erator and more particularly to a generator which is capable of generating a potential which may be varied at will in accordance with a trigonometric function of an angle.

It is often desirable to produce a potential which may be varied in accordance with a trigonometric function of an angle as for instance in accordance with the sine or cosine of an angle. An alternating current potential may be so varied through the use .of a magnetic resolver having two stator windings positioned in quadrature and a rotor winding to which the potential which is to be resolved is applied and which rotor is rotatable through a desired angle, whereby4 a potential is derived from one ,stator winding which is a function of the potential applied to the rotor winding and the sine of the angle through which the rotor is rotated and whereby a potential is derived from the other stator winding which is a function of the potential applied to the rotor winding and the cosine of the angle through which the rotor is rotated.

Another manner in which a sine or cosine derivative of either a direct or alternating `current potential may be ,secured is by means of a potentiometer, the winding of which is wound on a card which is so shaped that as the associated brush is moved over the winding to an amount commensurate with an angular displacement, the potential derived at the point of engagement of the brush with the winding will vary in accordance with either the sine or cosine of the angular displacement of the brush dependent upon whether the winding is wound for the derivation of a sine or of a cosine function of the potential applied across the potentiometer winding, l

In the application of W. H. 'I'. Holden Serial No. 527,999, filed March 24, 1944, a direct current generator has been disclosed from generatlng a potential which may be vvaried in accordance with the sine and cosine of an angle. In this generator, this is accomplished by the provision oi two pairs of brushes. positioned in quadrature with respect to eath other. The brushes may be mounted in a carrier rotatable with respect to the generator frame or preferably the brushes are xedly mounted on the generator frame and the vfield of the generator is rotatablewith respect thereto. With a generator thus constructed, it has been foundthat when the displacement of the brushes with respect to the polar axis of the held is equal to an angle, then 1944, Serial No. 544,534 I (Cl. r11-209) 2 a potential may be derived across one pair of brushes which varies in accordance with the sine of the angle and a potential may be derived across the other pair of brushes which varies 5 in accordance with the cosine of the angle. In s that application, the generator is employed as the master generator of an air position indicator, the generator being driven from the air mileage unit of the airplane at a speed which is commensurate with the air speed of the airplane and generating a, potential across its polar axis equal to Eo and a motor is operated to orient the brushes with respect to such polar axis through an angle Cs equal-to the true compass angle 'oi the flight, whereby the potential Es appearing across one pair of brushes is equal to Eo sin Cn and the potential Es appearing across the other pair of brushes is equal to Eo cos CN.

It is the object oi the present invention to 20 provide a direct current generator of the general type above described but of simpler construction and whereby the derived potentials more accurately follow the sine and cosine functions of a. varying angle.

One feature of the invention is the assemblage into a unified structure of two bipolar generators, the field pole-pieces and brushes of one generator unit being positioned in quadra.- ture with respect to the field pole-pieces and brushes of the other generator unit and with the corresponding ends of the pole-pieces of the two units positioned adjacent to each other and magnetizable by a rotatable permanent magnet whereby the magnet produces magnetization for the fields of both units of the generator assembly, v the intensities of which fields are varied one inf accordance with the sine of the angle through which the magnet is rotated and the other in accordance with the cosine of the angle. ,v

A further feature oi' the invention resides in the shaping of the ends of the pole-pieces in such a manner that the sine and cosine potentials generated by the two generator units vary 'accurately with the sine and cosine functions oi the angle through which the permanent magnet is rotated with respect to the polaritxes of the generators.

For a clearer understanding of the invention and the mode of its operation, reference may be had to the following detailed description thereof when read in connection with the accompanying drawings in which:

Fig. 1 is a side elevational view of the gen- 55 erator assembly of the present invention;

3 Fig. 2 is an end elevational view of the generato assembly; Y

Fig. 3 is a cross-sectional view taken along section line 3-3 of Fig. 1;

Fig. 4 is a cross-sectional view taken along section line 4-4 of Fig. l; Fig. 5 is a cross-sectional view taken along lsection line 5-5 of Fig. 1;

Fig. 6 is a fragmentary view, partly in crosssection, showing the manner in which the permanentmagnet which magnetizes the fields of the generator units is rotatably mounted;

Fig. l is a detailed view of the permanent magnet; and,

Fig. 8 shows the manner in which the abutting ends of the field pole-pieces of the two generator units are shaped and interposed.

As previously stated the generator assemblage in accordance with the present invention is essentially an assemblage of two generator units having their rotors mounted on the same shaft and -having their fields magnetically excited by a vbracket II of non-magnetic material having an supported therein a ball-bearing raceway Il, the Y axis of which is aligned with the axis of the tubularl portion 9 of the base member I. The ballbearing raceway serves as a support for one end of the rotor shaft Il.'

The two soft iron cld pole members Il and I1 of the generator unit 2 are secured to diametrically opposite portions ofthe peripheral surface of the hub memberV I4 by screws Il. The inner ends of these pole-piece members are widened out as best disclosed in Fig. 8 and as indicated by the dotted lines in Fig. 1 to form pole-pieces Il and 40, the adjacent edges of which are separated by narrow air-gaps 4I and 42. The pole members and I1 are secured to the inner surface of the tubular portion 8 of the base 3 by screws 4I.

Insulatedly supported in the pole member I1 adjacent toits outer end is a brush holder 44 ter- --minating in a threaded portion 4B on which is threaded a clamping nut 4l whereby a lead wire may be connected to the brush holder. A brush 41 is slidably supported in the brush holder, the

semblage to any desired support. At its central portion, the base 3 is provided with a web! extending at right angles from the plate 4 and having a tubular portion 9 formed integrally therewith with its axis extending parallel to the plate 4.

The generator unit I comprises an end-supporting bracket IU of non-magnetic material having an- L-shaped base II, the horizontal arm of which is secured to one end of the plate 4 by screws I2 and the vertical arm of which terminates in a cylindrical hub member I8. The

member I3 has supported therein a ball bearing raceway I4, the axis of which is aligned with the axis of the vtubular portion 8 of the base member 3. The ball-bearing raceway serves as a support for one end of the rotor shaft I5.

The two soft iron iield pole members I0 and I1 of the generator unit I are secured to diametrically opposite portions of the peripheral surface of the hub member Il by screws IB. The inner ends of these pole members are widened out asbest disclosed in Fig. 8 and as indicated by the dotted lines in Fig. 1 to form pole-pieces I9 and 20, the adjacent edges of which are separated by narrow air-gaps 2l and 22. The pole members II and I1 are secured to the inner surface of the tubular portion 9 of the base I by screws 23.

Insulatedly supported in the pole member I0 adjacent to the outer end thereof is a brush holder 24 terminating in a. threaded portion 25 on which is threaded a clamping nut 28 whereby a lead wire may be connected to the brush holder. A brush 21 is slidably supported in the brush holder, the inner end of which brush is forced into engagement with the rotor commutator 2l by the usual spring (not shown) which is interposed between the outer end of the brush and the outer end wall of the chamber within the holder 24. A similar brush holder 29 is insulatedly supported in the pole member l1 adjacent to its outer end.

Secured to the shaft Il and rotatable within the pole members Ii and I1-is a rotor I0 having a commutator 28.

The generator unit 2 is identical in construction to the unit I and comprises an end supporting inner end of which brush is forced into engagement with the rotor commutator 48 by the usual spring (not shown) which is interposed between the outer end of the brush and the outer endwall of the chamber within the holder 44. A similar brush holder 4l is insulatedly supported in the pole-piece member Il adjacent to its outer end.

Secured to the shaft I5 and rotatable within the pole members 38 and I1 is a rotor III having a commutator 4l.

Positioned within the pole-pieces Il, 2l, it and 4I is a cylindrical-permanent magnet Il. The magnet, disclosed in detail in Fig. 7, is magnetized more or less uniformly with one polarity over one half of its circumference and with the opposite polarity over the other half of its circumference and has a tubular sleeve l2 of non magnetic material extending axially therethrough, said magnet being non-rotatably se cured to the sleeve in any suitable manner. Becured to the sleeve adjacent to one end of the magnet or formed integrally with the sleeve is a bevel gear ll. The magnet and its assembled sleeve and gear are rotatably supported within the pole-pieces It, 20, I! and 4I with the peripheral surface of the magnet separated from the inner arcuate surfaces of the pole-pieces by a narrow air-gap 54 as seen in Figs. 3, 4 and 5.

For rotatably supporting the magnet Il, the

tubular portion i ofthe base 3 is provided at its end of the sleeve l2 on which the magnet Il is.

secured. In assembling the magnet Il within the pole-pieces of the pole-piece members Ii, 2l. l and 4l. the gear end of the sleeve l2 is inserted through the bearing hole In the ear 55 until the face of the gear l) lies adjacent to the inner face of the ear, then the ear I. is placed in position with the other end of the. sleeve I2 extending driven by any suitable means.

i are secured to the shaft is.

For rotating the magnet I with respect to the pole-pieces, a pinion gear BI is meshed with the gear 53 and is mounted on a shaft 59. The shaft 59 is journaled in an embossment 80 formed on the tubular portion 9 of the base 3 and may be To enable the shaft 5s and the magnet si lw be turned easily, a ball or roller bearing may be provided for shaft 59 in the embossment 80 and ball-bearings may be provided on the ears 5I and 58 for journalling the ends of the sleeve 52.

The rotors 30 and 5B of the two generator units One of the rotors is detachably secured to the shaft to enable the shaft to be inserted through the sleeve I2 on which the magnet 5I is mounted. The shaft when assembled in the ball-bearing raceways Il and 35 extends'freely through the sleeve 52.

The abutting pole-pieces I9, 20, 39 and I0 are shaped substantially as disclosed in Fig. 8, which figure illustrates a development of the four semicylindrical pole-pieces and the manner in which the two pole-pieces I9 and 20 of the generator unit I are disposed with respect to the pole-,pieces I9 andlll of the generator unit 2. It will be noted that the pole-pieces I9 and 20 are separated from the pole-pieces 39 and 40 by a sinusoidal air-gap B2 which crosses thesection line 3-3 at four points as disclosed in Fig. 3.

The generator functions in the following manner: It will be assumed that the permanent magnet 5I is rotated to a position in which its polar axis is aligned with the polar axis extending through the pole-members I6 and I1 and through the brushes of the generator unit I. Since the polar axis of the generator unit 2 is positioned in quadrature tothe polar axis of the generator unit I, the polar axis of the permanent magnet 5I will be 90 degres out of positional phase with the polar axis of the generator unit 2.

I Under this condition a maximum excitation of the field of generator unit I and a minimum excitation of the field of generatorunit 2 will resuit. If the shaft I5 is now rotated, thereby rotating the rotors 30 and 50 of the generator units I and 2, respectively, the generator unit I will generate a potential E1 which is the maximum for the speed of rotation of its rotor 30 and the generator unit 2 not having its field excited by the magnet 5I will generate no potential.

If the magnet 5I is rotated to a position in which its polar axis is aligned with the polar axis extending through the pole members $8 and 31 and through the brushes of the generator unit 2, then the polar axis to the magnet will be 90 degrees out of positional phase with the polar axis is the maximum for the speed of rotation of its rotor 80 and the generator unit I not having its field excited by the magnet 5I will generate no A potential.

It will now be 'assumed that through the shaft 59 and the gears 6I and I3, the magnet 5I is ro- `tated in a clockwise direction as viewed in Fig. 4,

from the position in which its polar axis is coincident with the polar axis of the generator unit I, through the angle 9. The polar axis of the `airplane flight.

.magnet 5I will now move away from coincidence with the polar axis of generator unit I and toward the polar axis of the generator unit 2, whereby the excitation of the field of generator unit I is decreased and the excitation ofthe field of generator unit 2 is increased fromzero in a positive direction. The potential generator by l the generator unit I may be expressed in terms E: will be equal to E1 and the potential E4 will `be zero and as the angle 6 increases toward 90 degrees potential Ea will decrease until when the y angle 0 becomes 90 degrees the potential E3 will be zero and the potential E4 will increase until when the angle 0 becomes 90 degrees, the potential E4 will be equal to Ez.

As the magnet BI is further rotated so that the angle 0 increases from 90 degrees toward degrees, the excitation of the field of generator unit 2 still remains positive but decreases and the excitation of the field of generator unit I is increased negatively from zero to a maximum whereby the potential E4 or Ez coso remains positive, but the potential Ea or E1 sin 0 becomes negative. As the magnet 5I is further rotated so that the angle o increases from 180 degrees toward 270 degrees, the excitation of the field of generator unit I still remains negative but decreases and the excitation of the field of generator unit 2 is increased negativelyv from zero to a maximum'whereby the potential Ez or E1 sin 0 decreases from a negative value to zero and the potential E4 or En cos 0 increases from aero to a maximum negative value. 5I is still further rotated from 270 degrees toward 360 degrees, the excitation of the field of gen-v scribed has particular utility in an air position indicator of the type disclosed in the application of W. H. T. Holden hereinbefore referred to. When used in a system of that type, the generator shaft I5 would be driven from the air mileage unit of the airplane so that the generator units would both generate reference potentials commensurate with the air speed of the airplane and the shaft 59 would be operated by the compass servo-motor to orient magnet-5I in accordance with the true compass course angle of the This use of the generator assembly is to be considered only as illustrative and not limiting it in any manner to such specific use. i

What is claimed is: y

1. A generator for generating a potential which may be caused to vary in accordance with a trigonometric function of an angle comprising a pair of soft iron pole-pieces, a rotor rotatable between said pole-pieces, each of said pole-pieces having a semi-cylindrically enlarged portion' at one end thereof, the adjacent edges of which portions are separated by narrow air-gaps, and a permanent magnet for magnetizing said pole- As the magnetA I pieces and rotatable with respect to the enlarged portions thereof through the angle for which the variable potential is desired.

2. A generator for generating a potential which may be caused to vary in accordance with a trigonometric function of an angle comprising a pair of soft iron pole-pieces, a rotor rotatable between said pole-pieces, each of said pole-pieces having a semi-cylindrically enlarged portion at -one end thereof, the adjacent edges of which portions are separated by narrow air-gaps, and a cylindrical di'ametrically magnetized permanent magnet rotatable within said enlarged portions through the angle for which the variable potential is desired.

3. A generator for generating a potential which may be caused to vary in accordance with a trigonometric function of an angle comprising a pair of soft iron pole-pieces, a rotor rotatable between said pole-pieces, a commutator brush holder mounted on each of said pole-pieces, a brush carried by each of said holders for cooperation with the commutator of said rotor, each of said pole-pieces having a 'semicylindrically enlarged portion at one end thereof, the adjacent edges of which portions are separated by narrow air-gaps and a cylindrical diametrically magnetized permanent magnet rotatable within said enlarged portions through the angle for which the variable potential-is desired.

4. A generator for generating a potential which may be caused to vary in accordance with.

a trigonometric function of an angle comprising a mounting plate, a cylindrical hub member secured to said plate at one end thereof, a tubular member secured to said plate having its axis aligned with the axis of said hub portion, a pair of soft iron pole-pieces each secured at one end to the peripheral surface of said hub member and at its other end to the inner surface of said tubular member, a rotor mounted for rotation within said pole-pieces, each of said pole-pieces having a semicylindrically-enlarged portion at the end secured to said tubular member, the adjacent edges of which portions are separated by narrow air-gaps, and a cylindrical diametrical'ly ma'gnetized permanent magnet rotatable within said enlarged portions through the angle for which the variable potential is desired.

5. A generator for generating a potential which may be caused to vary in accordance with a trigonometric function of an angle comprising a pair of soft iron pole-pieces, a rotor rotatable between said pole-pieces, each of said pole-pieces having a semicylindrically enlarged portion at one end thereof, the adjacent edges of which portions are separated by narrow air-gaps, and a cylindrical diametrically magnetized permanent magnet rotatable within said enlarged portions through the angle for which the variable poten tial is idesired, the ends of said enlarged portions being so shaped as to cause the generated potential to be varied by the rotation of said magnet in accordance with the trigonometric function of the angle through which said permanent magnet is rotated.

6. A generator for generating a potential which may be caused to vary in accordance with'the sine and cosine of an angle comprising a mounting plate, two pairs of soft Airon pole-pieces secured to said plate, one of said pairs being positioned in quadrature with respect to the other pair, a rotor shaft rotatably supported on said plate, a nrst rotor on said shaft for rotation within one pair of said pole-pieces, a second rotor on said shaft for rotation within the other pair of said pole-pieces, and a permanent magnet rotatable within both of said pairs of polepieces through a desired angle, whereby the rotation of one of said rotors generates a potential which varies in accordance with the sine of said angle and the rotation of the other of said rotors generates a potential which varies in accordance with the cosine of said angle.

7. A generator for generating potentials which may be caused to vary in accordance with the sine and cosine of an angle comprising a mounting plate, two pairs of soft iron pole-pieces secured to said plate and extending toward each other, one of said pairs being positioned in quadrature with respect to the other of said pairs and with the ends of the pole-pieces of one pair interposed between the adjacent ends of the pole pieces of the other pair, a rotor shaft rotatably supported on said plate, a first rotor on said shaft for rotation within one pair of said pole-pieces, a second rotor on said shaft rotatable within the other pair of said pole-pieces, and a permanent magnet rotatable within the interposed ends of all of said pole-pieces through a desired angle, whereby the rotation of one of said rotors generates a potential which varies in accordance with the sine of said angle and the rotation of the other of said rotors generates a potential which varies in accordance with the cosine of said angle.

8. A generator for generating potentials which may be caused to vary in accordance with the sine and cosine of an angle comprising a mounting plate, two pairs of soft iron pole-pieces secured to said plate and extending toward each other, one' of said pairs being positioned in quadrature with respect to the other pair, each of said pole-pieces having an enlarged pole portion and the enlarged pole portions of one of said pairs being interposed between the enlarged pole portions of the other pair and separated therefrom by narrow air-gaps, a rotor shaft rotatably supported on said plate, a first rotor on said shaft for rotation within one pair of said pole-pieces, a second rotor on said shaft rotatable within the other pair of said polepieces, and a permanent magnet rotatable within the interposed enlarged portions of said polepieces through a desired angle, whereby the rotation of one of said rotors generates a potential which varies in accordance with the sine of said angle and the rotation of the other of said rotors generates a. potential which varies in accordance with the cosine of said angle.

9. A generator for generating potentials which may be caused to vary in accordance with the sine and cosine of an angle comprising a mounting plate, two pairs of soft iron pole-pieces secured to said plate and extending toward each other, one of said pairs being positioned in quadrature with respect to the other pair, each of said pole-pieces having a substantially sinusoidally shaped pole portion and the pole portions of one of said pairs being interposed between the pole portions of the other of said pairs and separated therefrom by a narrow sinusoidaliy contoured air-gap, a rotor shaft rotatably supported on said plate, a firstrotor on said shaft for rotation within one pair of said pole-pieces, a second rotor on said shaft rotatable within the other pair of said pole-pieces, and a cylindrical diametrically magnetized permanent magnet rotatable within the interposed pole portions of said pole-pieces through a desired angle, whereby the rotation of one of said rotors generates a potential which varies in accordance with the sine of said angle and the rotation of the other of said rotors generates a potential which varies in accordance with the cosine of said angle.

10. A generator for generating potentials which may be caused to vary in accordance with the sine and cosine of an angle comprising a mounting plate, cylindrical hub members secured to the opposite ends of said plate respectively, a

` tubular member secured to the central portionL of said plate, with its axis aligned win the axes of said hub members, a rst pair of soft iron pole-pieces each secured at one end to the peripheral surface of one of said hub members and at its other end to the inner surface of said tubular member, a second pair of soft iron polepieces each secured at one end to the peripheral surface of the other of said hub members and at its other end to the inner surfacey of said tubular member, each of the ends of the pole-pieces which is secured to said tubular member being sinusoidally shaped and such shaped ends of one pair of said pole-pieces being interposed between the shaped ends of the other pair of said pole-pieces and separated therefrom by a narrow sinusoidally contoured air-gap, a rotor potential which varies in accordance with the cosine ofv said angle.

WILLIAM H. T. HOLDEN. EDMUND R. MORTON. I

REFERENCES CITED The following references are of record in the file of this patent:

UNrrEn s'rA'rEs PATENTS f Number Name Date 819,933 Schneider May 8, .1906

FOREIGN PATENTS Number Country Date German June 20. 1910 

